Chances are you've used several solenoids at some point today. They help you start your car, ring your doorbell, and do hundreds of other things for you every day. But what is a solenoid and how does a solenoid work?
A solenoid works by producing an electromagnetic field around a moving core, called an armature. When forced to move by the electromagnetic field, the movement of this armature opens and closes valves or switches and transforms electrical energy into mechanical motion and force.
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For being such a big part of our world, solenoids are simple mechanisms that require only a basic understanding of the physics that most of us learned in college. Understanding them is not difficult and you don't need to know any mathematical formulas to learn their secrets.
WHAT IS A SOLENOID?
At the simplest level, a solenoid is a length of wire wrapped around a core. The core often has two parts - a fixed core and a moving one, which is the armature. Both parts are spring loaded.
When electric current flows through the wire, it creates a magnetic field that pulls the armature away from (or toward) the fixed core, depending on the use and construction of the solenoid. When the current stops, the spring returns the armature to its original position.
To work, a solenoid must have three things:
- A coiled wire
- A moving core
- Electricity
In a car's ignition system, these elements combine to move the armature, completing the circuit that lights your engine. Once you release your key and it moves away from the "start" position, the solenoid deactivates, the armature returns to its previous position, breaking the circuit. This way, your car's ignition stops trying to start the engine, because it is already running.
Solenoid Basics Explained - Working Principle
WHAT IS A SOLENOID VALVE?
Solenoid valves are like any other valve in that they regulate the flow of gases or liquids. The presence of a solenoid in them allows these valves to open or close via electricity.
These types of valves can be made in two different ways: normally open and normally closed.
In the rest position of a solenoid valve - off - no current flows through the wires and the moving core rests against the base of the valve. In doing so, it seals the valve, as the liquid or gas behind it cannot pass through.
Sending electricity through the wire coil creates the magnetic field, this field causes the core to lift and the liquid or gas can now pass freely through the valve. Turning off the electricity causes the core to drop back down, closing the valve and cutting off the flow of gas or liquid. This is the function of a normally closed valve, which remains closed until electricity is used to open the valve.
A normally open solenoid valve uses the same basic principles, but is designed to operate in the opposite direction. When in the off position, the core remains in the up position, allowing fluid to flow through the open valve. Energizing the valve will force the core down, shutting off the flow and closing the valve.
How Does a Starter Solenoid Work?
Applications
Stronger or weaker solenoids can be used as required. A large powerful solenoid with many coils and a large electric current is not needed to ring your doorbell. A small solenoid can accomplish this.
But a solenoid on an oil derrick should be much more powerful. Although all solenoids are electric - you can't have an electromagnet without electricity - the variety of tasks they perform requires different types.
- Electric. This term governs all solenoid valves because electricity must be involved.
- Pneumatic solenoid valve. These solenoid valves allow the movement and removal of gases such as air, nitrogen and carbon dioxide.
- Hydraulic. A valve that governs the movement of liquids, from water to bourbon to gasoline.
When you start looking for them, you'll find that solenoids and solenoid valves are ubiquitous in modern life and make many of the tasks we perform every day much easier to manage.
TESTING A SOLENOID
Your solenoid valve may stop opening and closing from time to time, or your car's solenoid may not start your car one day. Diagnosing these problems is key to fixing them, so there are few simple ways to do it.
The easiest way is to use a compass. Because your solenoid works on electromagnetism, there will be no magnetic field surrounding it if the solenoid itself is not working.
By placing a compass near the solenoid, and then activating the solenoid, you'll know immediately if that's the problem or if there's some other mechanical problem. If your compass needle jumps, the solenoid has created a magnetic field. If not, your solenoid is not receiving the electricity it needs.
In this case, you can further determine the problem with a multimeter. Before doing so, however, your first step is to check the connections. If your positive or negative terminals are disconnected or defective in any way, the solenoid cannot function even if it is in perfect condition. Even if the connections look good, you must use your multimeter to determine the continuity of the solenoid.
Once you have determined that the connections are good, set your multimeter to its resistance setting. If you get a reading greater than 0.3 ohms, the device is not working as it should. It is not conducting enough electricity to operate and should be replaced.
For more information on how to diagnose and solve a problem, check out our solenoid valve troubleshooting resource.
CONCLUSION
Solenoids and solenoid valves are found almost everywhere in our modern world. We use them to start cars, run dialysis machines, control dishwashers, and even manipulate our speakers to produce music from an electrical signal. While our lives would be very different without them, solenoids are simple creations.
Requiring only wire, a magnetic core, and an electric current, functional solenoids can be made in a college science class, but they help us accomplish hundreds of tasks, some of which would be impossible without them.